1. Field of the Invention
Our invention is a device for removing condensate from the vapor lines of pressurized vapor systems. It incorporates an orifice and a strainer. References to such devices were found in the following places in the search files of the U.S. Patent and Trademark Office: Class 137, Fluid Handling; Subclass 171, Diverse Fluid Containing Pressure Systems, Fluid separating traps or vents; Subclass 177, Discriminating outlet for liquid. Class 55, Gas Separation; Subclass 466, With Separated Nongaseous Material Conducting or Treating Means; Digest 23, Steam Separators.
2. Description of the Prior Art
A "List of Prior Art Cited by Applicant," Form PTO-1449, is attached. This form lists the following references:
Ref. AA--U.S. Pat. No. 2,636,506, PA1 AB--U.S. Pat. No. 2,020,563, PA1 AC--U.S. Pat. No. 3,893,473, PA1 AD--U.S. Pat. No. 3,715,870, PA1 AE--U.S. Pat. No. 3,877,895, PA1 AR--Flexitallic Gasket Co. Inc. Bulletin 776, "Flexitallic Drain Orifice."
Reference AA discloses a condesation drainer which incorporates an orifice. It is well known to use an orifice for draining condensate from steam lines; the orifice is sized to allow passage of the condensate approximately as fast as it is formed in the line in which it is installed, yet not so fast as to allow an excessive amount of steam to escape through the orifice.
Reference AA also shows a strainer incorporated in the device for removing "scale, rust or other sediment" to obviate "clogging or abrading of the orifice . . . "
The Reference AA device has drawbacks which our invention overcomes. Our invention has the orifice located within the envelope of the strainer, resulting in a much more compact device, lighter in weight and more sparing of materials; it is obviously a much simpler configuration. Our device is not attitude sensitive; it may be mounted in any position, while the Reference AA device appears to require mounting in the position shown in order to affect "a liquid seal for the orifice fitting 28." Our device has a single gasketed joint between atmosphere and system pressure (discounting the joints between line and device) whereas the Reference AA device has four tapered thread joints which are prone to leakage and seizing and which must be carefully resealed by a cumbersome process after being opened.
Reference AB also discloses a condensate removing device incorporating an orifice and a strainer. The orifice, however, is spaced from the strainer, resulting in a larger, heavier device. The device is also more complex, it is attitude sensitive and it has four sealed joints as opposed to just one.
Reference AC shows a condensate drainer with an integral strainer, but the device does not use an orifice in the strict sense of that term. As such it is only marginally relevant as prior art. In any case, it contains a moving part in contradistinction to our invention, and has three sealed joints rather than just one.
References AD and AE both show condensate removal devices incorporating an orifice and an integral strainer. As Reference AR discloses, however, it is necessary when using Reference AE devices with orifices smaller than 0.125 in. (3.175 mm) to install a strainer upstream of the device, the screen in the Reference AE device serving admittedly as only secondary protection.
The reason the Reference AE/AR device requires an upstream strainer is that, by itself, the area of the screen is too small; it quickly becomes clogged and needs cleaning. This can be a serious deficiency in certain critical applications, for example in the line providing steam to a ship's propulsion turbine or to a turbine generating electrical power. If the strainer becomes clogged, condensate will not be removed at the proper rate and may enter the turbine where its effects can be catastrophic.
Our invention overcomes this deficiency by providing a combination strainer/orifice which has a much larger area of strainer than the Reference AE/AR device by itself, yet which has approximately the same space envelope. Thus, it is possible with our invention to use a strainer fine enough to accommodate a larger range of orifice sizes, including those much smaller than 3.175 mm. Our invention therefore substitutes one component for two--the Reference AE/AR device and an upstream strainer--and is consequently cheaper, easier to install and maintain, lighter and takes less space.
In applications where the orifice size is 3.175 mm or larger and it is not necessary to use an upstream strainer with the Reference AE/AR device, our invention still has important advantages: with the larger surface area of strainer, our device will not lose effectiveness as fact as the Reference AE/AR device and will thus be more reliable and need less frequent maintenance. Furthermore, whereas the Reference AE/AR device is attitude sensitive--if it is installed in a vertical line, for instance, particles passing through the screen tend to fall on the orifice-our invention is not. Regardless of the orientation, any particles which may by chance pass through the strainer of our device tend to collect at places other than on the orifice.
Our invention is also easier to maintain and inspect than the Reference AE/AR device. This is particularly so in those applications where the Reference AE/AR device requires an upstream strainer as then it is necessary to deal with two components rather than one. But just comparing one for one, our device is more advantageous. It requires the removal of only four nuts to expose both the orifice and strainer for inspection, cleaning or replacement. The orifice need not be removed for inspection. In reassembling, only one gasket is involved and the operation is very simple. The Reference AE/AR device requires first the removal of a number (larger than four, depending on rated size) of flange bolts. Then the flanges must be sprung or jacked apart before the screen and orifice plate can be exposed. Two gaskets are required for the device rather than just one, and the reassembly procedure requires more care in positioning of parts. In a direct comparison with Reference AE/AR devices with upstream strainers our invention required much less than half the time to disassemble, inspect, clean and reassemble.
A further advantage of our invention inheres in the single sealed joint: in general, the more joints the more prone to leakage. The Reference AE/AR device, as noted, has two sealed joints between system pressure and atmosphere; the provision of an upstream strainer adds at least one more joint.